Preparation,Optimization And Application Of Calcium Carbonate Stabilized Pickering Emulsions

Solid particles stabilized emulsions,so called Pickering emulsions,is getting increasing interests among researchers for their advantages of easy preparation,high stability,functional versatility,adjustable wettability and economical friendly.Researches on Pickering emulsions are of great importance in food industry,cosmetic industry and bio-pharmaceuticals area.Researchers have investigated systematically on Pickering emulsions,different kinds of solid particles can be used to stabilize Pickering emulsions,including carbohydrate-based particles,such as modified starch,cellulose;protein-based particles,such as zein,soy protein;and inorganic particles including SiO₂,clay.CaCO₃ is a kind of widespread and inexpensive inorganic particles with good biocompatibility.However,there are little research on CaCO₃ stabilized emulsions.Therefore,we prepared emulsions stabilized by CaCO₃;optimized the emulsions by adding sodium alginate;encapsulated and delivered curcumin,a kind of fat-soluble nutrient,and investigated the influence of emulsion properties on curcumin release.Here are the main research contents and results:1.Research on O/W Pickering emulsions stabilized by CaCO₃ and their particle size effect.Food grade CaCO₃ was used as stabilizer to prepare O/W Pickering emulsions.CaCO₃ of different particle size were obtained by ball milling method,and the effects of particle size,particle concentration and ratio of water to oil on type,stability,micro-morphology and rheology property of the emulsions were investigated.The results indicated that Ball-milled CaCO₃ can stabilize Pickering emulsions,and the emulsion was stable after long-term storage.Particle size of CaCO₃ had effect on the stability of emulsions and drop size of the emulsion increased with expansion of the particle size.When particle concentration was increased,the creaming index,drop size of emulsions decreased,but the viscosity of the emulsions increased.However,when CaCO₃concentration>9 wt%,there was little influence of particle concentration on drop size.Emulsion index,drop size and viscosity of emulsions grew with the increase of the ratio of water to oil.2.Research on Pickering emulsions stabilized by CaCO₃ and sodium alginatePickering emulsion stabilized by CaCO₃ and sodium alginate were prepared through a two-step method.Compared to CaCO₃ stabilized emulsions,the CaCO₃/Alg stabilized emulsions exhibits an improved stability,they showed different flow behavior at different addition volume of Alg after one month of storage.Dynamic light scattering?DLS?was used to monitoring the changes of volume-average droplet size during the storage time,confocal laser scanning microscope?CLSM?was applied to observe the adsorption of CaCO₃ particles and Alg on the oil-water interface.In addition,the emulsions were characterized by rheology and microrheoloy measurement,which indicated the gel-like network forming during the storage time.Specifically,strong gel-like network developed and emulsion gel formed at low Alg concentration after stored for 17 days.However,at higher Alg concentration,CaCO₃ particles were almost covered by Alg,little calcium cations were released to cross-link with Alg as time went on,thus weak gel-like network formed on the oil-water interface and making the emulsions more stable during the long-term storage.3.Encapsulation and delivery of curcumin.Curcumin was chosen to be the drug model for the in vitro investigation of the release behavior of CaCO₃/Alg emulsions.In simulate gastric fluid,the curcumin release rate reached 80%in 30 min for the emulsions stabilized solely by CaCO₃,while the release rates were about 30%for emulsions stabilized by CaCO₃ and Alg of different concentration,which indicated that the CaCO₃/Alg stabilized emulsions could protect curcumin in the simulate gastric fluid.In simulate intestinal fluid,the final curcumin release rate reached 85%,which indicated that the CaCO₃/Alg emulsions showed pH-responsiveness,and it could be used as the delivery system of enteric soluble drugs.